C++ 信号处理

C++ 信号处理

 

[root@flink mediaC]# g++ main.cpp ; ./a.out;
Going to sleep...
Going to sleep...
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...

#include <iostream>
#include <csignal>
#include <unistd.h>

using namespace std;

void signalHandler(int signum) {
	cout << "Interrupt signal ( "<<signum<<" ) received.\n";
	// 清理并关闭
	// 终止程序
	// exit(signum);
}

int main() {
	// 注册信号SIGINT和信号处理程序
	signal(SIGINT,signalHandler);
	while(1) {
		cout<<"Going to sleep..."<<endl;
		sleep(1);
	}
	return 0;
}

　　

当上面的代码被编译和执行时，它会产生下列结果：

Going to sleep....
Going to sleep....
Going to sleep....

现在，按 Ctrl+C 来中断程序，您会看到程序捕获信号，程序打印如下内容并退出：

Going to sleep....
Going to sleep....
Going to sleep....
Interrupt signal (2) received.

Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
^CInterrupt signal ( 2 ) received.
Going to sleep...
Going to sleep...
Going to sleep...
Going to sleep...

 

 

无法终止

 

#include <iostream>
#include <csignal>

using namespace std;

void signalHandler(int signum) {
	cout << "Interrupt signal ( "<<signum<<" ) received.\n";
	// 清理并关闭
	// 终止程序
	// exit(signum);
}

int main() {
	int i =0 ;
	// 注册信号SIGINT和信号处理程序
	signal(SIGINT,signalHandler);
	while(++i) {
		cout<<"Going to sleep..."<<endl;
		if(i==3) {
			raise(SIGINT);
		}
		sleep(1);
	}
	return 0;
}

　　

raise() 函数

您可以使用函数 raise() 生成信号，该函数带有一个整数信号编号作为参数，语法如下：

int raise (signal sig);

在这里，sig 是要发送的信号的编号，这些信号包括：SIGINT、SIGABRT、SIGFPE、SIGILL、SIGSEGV、SIGTERM、SIGHUP。以下是我们使用 raise() 函数内部生成信号的实例：

 

信号是由操作系统传给进程的中断，会提早终止一个程序。在 UNIX、LINUX、Mac OS X 或 Windows 系统上，可以通过按 Ctrl+C 产生中断。

有些信号不能被程序捕获，但是下表所列信号可以在程序中捕获，并可以基于信号采取适当的动作。这些信号是定义在 C++ 头文件 <csignal> 中。

信号	描述
SIGABRT	程序的异常终止，如调用 abort。
SIGFPE	错误的算术运算，比如除以零或导致溢出的操作。
SIGILL	检测非法指令。
SIGINT	接收到交互注意信号。
SIGSEGV	非法访问内存。
SIGTERM	发送到程序的终止请求。